The invention relates to new volatile organic barium, strontium and calcium compounds.
Volatile organic barium, strontium and calcium compounds are known.
P. H. Dickinson, A. Sanjurjo, T. H. Geballe, D. Hildenbrandt, G. Graig, M. Zisk, J. Collman, S. A. Banning and R. E. Sievers for instance, in J.Appl.Phys.1989, 66, 444, describe the use of the 2,2,6,6-tetramethyl-3,5-heptanedione (thd) compound of--among others--Ba, that is {Ba(thd).sub.2 }, as precursor for so-called chemical vapor deposition (CVD) processes. This compound has been found to dissociate partially during evaporation, because of which its concentration in the vapor phase diminishes as a function of time, at a constant temperature of the source, in this case Ba(thd).sub.2 in the solid phase.
Other volatile barium-, strontium- and calcium-.beta.-diketonates are also known, for instance from the work of J. E. Schwarberg, R. E. Sievers and R. W. Moshier, in Anal.Chem. 1970, 42, 1828. It has been found, however, that when these compounds are heated to 200.degree. C. and higher temperatures, which is necessary to bring them from the solid phase into the gas phase, a rapid decomposition occurs.
Barium-, strontium- and calcium-.beta.-diketonates are described--among others--by D. E. Fenton in "Comprehensive Coordination Chemistry", Editor in Chief G. Wilkinson, in Volume 3, Chapter 23.4.1., pages 25 and on.
It has now been found that the problems encountered with known volatile compounds so far can be overcome by applying certain combinations of barium-, strontium- and calcium-.beta.-diketonates and coordinating ligands.